
Re: Simple versus formal proof?
Posted:
Jun 23, 2006 9:49 AM


Mohab wrote: > for the last term to be even, one must assume that (k^2 + k) must be even, > but that is what you are trying to prove.
Erm, this is the inductive step. The basis step is to show that k^2 + k is even for some small value of k, such as 1.
1^ + 1 = 2 tick
Now show that if it holds for k it also holds for k+1
(k+1)^2 + (k+1) = k^2 + k + 2k + 2 tick
I.e. we have the value for k, known to be even, plus 2(k+1), also even. Surely in the induction step k^2 + k is the hypothesis, not the subgoal to be proved?
Cheers,
Rossc

